The present invention relates to traps used to trap and manipulate particles, and particularly relates to optical traps that employ electromagnetic fields to trap and manipulate micro-particles.
Optical traps generally involve the use of a beam or focused field of electromagnetic energy that may be directed toward a small sample particle (on the order of an atom to as large as even tens of micrometers). The electromagnetic energy may be absorbed, reflected or refracted, and the small forces associated with such absorption, reflection or refraction may be used to trap or move the small sample particle. For example, U.S. Pat. No. 5,512,745 discloses a system and method for optically trapping micrometer-sized spheres to which molecules may be attached. The system includes a feedback circuit that utilizes a quadrant photodetector and a focal region location unit such as an acousto-optic modulator or galvanometer mirror. U.S. Pat. No. 5,620,857 also discloses a system in which sample elements such as analytes are adhered to polarized microspheres of glass or latex with diameters on the order of 4.5 μm. The analytes are detected and quantitated in accordance with disclosed systems.
Such systems, however, require the use of multiple laser beams in order to provide multiple optical traps (or light tweezers as they are sometimes called) to manipulate multiple samples simultaneously. Moreover, it is not practical in certain applications to employ more than one light trap in a small sample region.
There is a need therefore, for a system and method for efficiently and economically providing for multiple optical traps.